Molecular Regulation of Salt Stress Tolerance in Fruit Crops with Special Emphasis on WRKY Transcription Factors

Soil salinity is one of the most severe abiotic stresses limiting fruit crop productivity worldwide. Increasing salinization of agricultural lands due to climate change, irrigation mismanagement, and seawater intrusion has intensified the need for developing salt-tolerant fruit crops. Plants respond to salt stress through complex molecular, physiological, and biochemical mechanisms involving stress perception, signal transduction, transcriptional regulation, and metabolic adjustment. Among the various regulatory components, transcription factors play a pivotal role in orchestrating stress-responsive gene networks. WRKY transcription factors represent one of the largest plant-specific transcription factor families and have emerged as key regulators of plant responses to salinity stress. In fruit crops, WRKY proteins regulate ion homeostasis, osmotic adjustment, reactive oxygen species scavenging, hormonal signaling, and stress-induced gene expression. Recent advances in genomics, transcriptomics, and functional studies have revealed the involvement of WRKY genes in enhancing salt tolerance in several fruit species. This review provides a comprehensive overview of salt stress effects on fruit crops, molecular mechanisms of salt tolerance, structure and classification of WRKY transcription factors, and their specific roles in regulating salt stress responses. Furthermore, recent biotechnological and breeding approaches exploiting WRKY genes for improving salt tolerance in fruit crops are discussed, highlighting future perspectives for developing climate-resilient horticultural systems.